Automatic Machine Condition Indicator Integrated with Airborne Capacitive Plate to Monitor Partial Discharge and Arc Signal from High Voltage Electric Equipment

In this paper, the signals of partial discharge and electric arc picked up on metal surface of electric equipment such as switch gear and distributing board, rotating machine and dry transformer are analyzed in magnitude, frequency and time domain. And a novel monitoring system, AMCI (Automatic Machine Condition Indicator), equipped with four ACP sensors (TEV sensor, airborne capacitive probe) is introduced to monitor the health status of high voltage equipment. ACP shows the wider frequency band response of 2MHz-50MHz to airborne partial discharge and arc signal. The probe could be, magnetically, attached on steel panel of electrical equipment. Obviously, the key technology is the discrimination scheme to extract only partial discharge and arc signal from the detected signal. In this context, SDA (Signal Differentiation Analysis) introduced in the other paper is adopted to remove external noise. The next issue is the elimination of interference signals due to radiation effect and common mode voltage. Not only severe PD and arc activities from a target electrical equipment but attenuated radiation signals from an adjacent electric equipment are detected by ACP sensors due to the radiation effect from one metal plate to the others and common mode voltage effect. The 3PSD_SS (3 Phase Signal Detection in a Single Sweep) is introduced to eliminate the adjacent signal interference effect.